Abstract

A scheme for neutron production is investigated in which an ultra-intense laser is
irradiated into a two-layer (deuterium and aurum) spherical shell target through the cone
shaped entrance hole. It is found that the energy conversion efficiency from laser to target can reach
as high as 71%, and deuterium ions are heated to a maximum energy of several MeV from the
inner layer surface. These ions are accelerated towards the center of the cavity and
accumulated finally with a high density up to tens of critical density in several
picoseconds. Two different mechanisms account for the efficient yield of the
neutrons in the
cavity: (1) At the early stage, the neutrons are generated by the high energy deuterium ions based on
the “beam-target” approach. (2) At the later stage, the neutrons are generated by the
thermonuclear fusion when the most of the deuterium ions reach equilibrium in the
cavity. It is also found that a large number of deuterium ions accelerated inward can pass
through the target center and the outer Au layer and finally stopped in the CD2 layer.
This also causes efficient yield of neutrons inside the CD2 layer due to
“beam-target” approach. A postprocessor has been designed to evaluate the neutron yield and the
neutron spectrum
is obtained.

The authors acknowledge Bo Yang and Jia Wang for supporting the data of cross section of
neutrons and the data of stopping power. This work was supported by National Natural Science
Foundation of China (Grant Nos. 11305013, 91230205, 11175030, 11475030, 11147025, 11274152,
and 11275028), the National Key Basic Research Program of China (Grant No. 2013CBA01500),
and National High Technology and Development Program of China.